Edit File Lines MCP Server

Overview

The Edit File Lines MCP Server is a TypeScript‑based tool that empowers AI assistants to perform fine‑grained, line‑by‑line modifications on source files within a controlled set of directories. Rather than sending whole file diffs, the server exposes a single, expressive operation——that accepts a list of edit descriptors. Each descriptor can target specific line ranges, match exact strings or regular expressions, and replace either entire lines or portions of them while preserving surrounding whitespace and indentation. This granular control is essential for developers who need to patch code, update configuration snippets, or refactor components without disrupting formatting or introducing syntax errors.

Why It Matters

When AI assistants generate code suggestions, they often produce snippets that must be merged into existing projects. Manual copy‑paste is error‑prone and can break build pipelines if indentation or comments are mangled. The MCP server solves this by providing a deterministic, dry‑run preview mode that shows the exact diff before any change is committed. Developers can review the proposed modifications, approve or reject them via an call that references a unique state ID returned by the server. This workflow mirrors code review practices, giving teams confidence that AI‑driven edits are safe and traceable.

Key Capabilities

• Line‑range targeting: Specify start and end lines to replace whole blocks or single statements.
• String & regex matching: Choose between exact text matches or complex patterns to locate code fragments, even across multiple lines.
• Whitespace preservation: The server retains original indentation and spacing when only parts of a line are altered, preventing formatting regressions.
• Dry‑run previews: Generate unified diffs that highlight changes, enabling instant visual inspection before approval.
• Batch edits: Submit multiple edit objects in a single request, allowing coordinated refactors or bulk configuration updates.

Real‑World Use Cases

• Component refactoring: Update props, rename variables, or adjust styling classes in React components while keeping the surrounding JSX intact.
• Configuration management: Edit JSON or TypeScript configuration files to toggle feature flags, update URLs, or adjust timeout values without breaking the file’s structure.
• Automated code cleanup: Remove deprecated imports, replace legacy API calls, or apply linting fixes across large codebases in a single operation.
• CI/CD pipeline integration: Run the MCP server as part of automated testing, generating diffs that can be automatically approved by a bot if they match predefined safety criteria.

Integration with AI Workflows

Developers can embed the server in an AI‑assisted development pipeline by exposing its tool to a Claude or similar assistant. The AI can then propose edits in natural language, which the server translates into precise line modifications. Because the server returns a state ID and a diff preview, developers can incorporate these changes into pull requests or automated merge processes. The dry‑run feature also allows continuous integration systems to validate edits before they touch the main branch, ensuring that AI contributions do not introduce regressions.

Standout Advantages

• Fine‑grained control: Unlike generic patch tools, the server’s line‑based API is tailored for source code editing, preserving formatting and reducing merge conflicts.
• Safety first: The mandatory dry‑run preview and approval step make it suitable for production environments where accidental code changes are unacceptable.
• Developer‑friendly: The API is simple, documented, and designed to work seamlessly with existing MCP clients, requiring no additional tooling or configuration beyond the server itself.

In summary, the Edit File Lines MCP Server provides a robust, developer‑centric solution for AI‑driven code modifications, combining precision editing, safety checks, and seamless integration into modern development workflows.